1. Field of the Invention
The present invention relates to a substrate treatment apparatus which treats a substrate such as a semiconductor wafer, a glass substrate for a liquid crystal display device, a substrate for a plasma display device, a substrate for a FED (Field Emission Display) device, a substrate for an optical disk, a substrate for a magnetic disk, a substrate for a magneto-optical disk, and a substrate for a photo mask.
2. Description of Related Art
In production processes for semiconductor devices and liquid crystal display devices, a substrate such as a semiconductor wafer or a glass substrate for a liquid crystal display panel is treated with a treatment liquid and a treatment gas. For example, a substrate treatment apparatus of a single substrate treatment type adapted to treat a single substrate at a time includes a spin chuck which horizontally holds and rotates the substrate, a nozzle which supplies the treatment liquid to a surface of the substrate held by the spin chuck, and a bottomed tubular treatment cup in which the spin chuck is accommodated. The spin chuck, the nozzle and the treatment cup are accommodated in a treatment chamber.
During the treatment of the substrate, an upward gas current occurs around the spin chuck due to the rotation of the substrate and the spin chuck. The upward gas current causes the mist of the treatment liquid to soar and spread in the treatment chamber, so that the interior wall of the treatment chamber and components disposed in the treatment chamber are contaminated with the mist of the treatment liquid. If the mist of the treatment liquid is dried in the treatment chamber, particles resulting from the dried treatment liquid float in the atmosphere, leading to contamination of a substrate to be subsequently treated. To cope with this, an FFU (fan filter unit) is provided at the center of a ceiling of the treatment chamber. A downward gas current is produced in the treatment cup by supplying clean air downward from a gas supply port of the FFU and venting the air from a gas outlet port provided in a bottom of the treatment cup.
In order to suppress the soaring of the treatment liquid mist and the like in a space of the treatment chamber outside the treatment cup, the internal atmosphere of the treatment chamber is vented through a gas outlet port provided in a bottom of the treatment chamber to produce a downward gas current toward the gas outlet port, whereby the ventilation of the internal atmosphere of the treatment chamber is promoted.
Further, a shield member is provided, for example, in opposed relation to the surface (upper surface) of the substrate held by the spin chuck in the treatment chamber for shielding a space above the surface of the substrate from the ambient atmosphere (see, for example, Japanese Unexamined Patent Publication No. 2006-202983).
With the gas supply port of the FFU disposed above the shield member, however, the shield member prevents the flow of the clean air to disturb the gas current in the treatment chamber. Therefore, the convection of the atmosphere is liable to occur in the treatment chamber. Particularly, during the rotation of the spin chuck, the upward gas current described above is liable to disturb the gas current in the treatment chamber. This is a major factor that makes it difficult to stably produce the downward gas current in the space of the treatment chamber outside the treatment cup.
In order to stabilize the gas current in the treatment chamber and promote the ventilation of the internal atmosphere of the treatment chamber, a higher gas venting capability is required to vent the air from the gas outlet port provided in the bottom of the treatment chamber. However, a plant in which the substrate treatment apparatus is installed has a limitation in available gas venting capacity, making it difficult to provide a gas venting capability necessary for stabilization of the gas current.